package com.utils;

import org.apache.commons.codec.binary.Base64;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.security.SecureRandom;
import java.util.Objects;
import java.util.Random;

/**
 * AesEncryptUtil.java
 *
 * @author Liang 649355204@qq.com
 * CreateTime 2019/7/17 16:56
 */
public class AesEncryptUtil {
    /** 使用AES-128-CBC加密模式，key需要为16位,key和iv可以相同！ */
    private static String KEY = "1234567890123456";
    private static String IV = "1234567890123456";

    /**
     * 加密方法
     *
     * @param data 要加密的数据
     * @param key  加密key
     * @param iv   加密iv
     * @return 加密的结果
     * @throws Exception 加密失败抛出异常
     */
    public static String encrypt(String data, String key, String iv) throws Exception {
        try {
            // "算法/模式/补码方式"NoPadding PkcsPadding
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
            int blockSize = cipher.getBlockSize();

            byte[] dataBytes = data.getBytes();
            int plaintextLength = dataBytes.length;
            if (plaintextLength % blockSize != 0) {
                plaintextLength = plaintextLength + (blockSize - (plaintextLength % blockSize));
            }

            byte[] plaintext = new byte[plaintextLength];
            System.arraycopy(dataBytes, 0, plaintext, 0, dataBytes.length);

            SecretKeySpec keyspec = new SecretKeySpec(key.getBytes(), "AES");
            IvParameterSpec ivspec = new IvParameterSpec(iv.getBytes());

            cipher.init(Cipher.ENCRYPT_MODE, keyspec, ivspec);
            byte[] encrypted = cipher.doFinal(plaintext);

            return new Base64().encodeToString(encrypted);

        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 解密方法
     *
     * @param data 要解密的数据
     * @param key  解密key
     * @param iv   解密iv
     * @return 解密的结果
     * @throws Exception 加密失败抛出异常
     */
    public static String desEncrypt(String data, String key, String iv) throws Exception {
        try {
            byte[] encrypted1 = new Base64().decode(data);

            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
            SecretKeySpec keyspec = new SecretKeySpec(key.getBytes(), "AES");
            IvParameterSpec ivspec = new IvParameterSpec(iv.getBytes());

            cipher.init(Cipher.DECRYPT_MODE, keyspec, ivspec);

            byte[] original = cipher.doFinal(encrypted1);
            return new String(original, StandardCharsets.UTF_8);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 使用默认的key和给定的iv加密
     *
     * @param data 要加密的内容
     * @param iv 加密的IV
     * @return 加密后的内容
     * @throws Exception 加密失败抛出异常
     */
    public static String encrypt(String data, String iv) throws Exception {
        return encrypt(data, KEY, iv);
    }

    /**
     * 使用默认的key和iv加密
     *
     * @param data 要加密的内容
     * @return 加密后的内容
     * @throws Exception 加密失败抛出异常
     */
    public static String encrypt(String data) throws Exception {
        return encrypt(data, KEY, IV);
    }

    /**
     * 使用默认的key和iv解密
     *
     * @param data 密文
     * @return 解密后的内容
     * @throws Exception 解密失败抛出异常
     */
    public static String desEncrypt(String data) throws Exception {
        return desEncrypt(data, KEY, IV);
    }

    /**
     * 使用默认key和传输的iv解密
     *
     * @param data 密文
     * @param iv 加密的IV
     * @return 解密后的内容
     * @throws Exception 解密失败抛出异常
     */
    public static String desEncrypt(String data, String iv) throws Exception {
        return desEncrypt(data, KEY, iv);
    }

    public static String randomString() {
        return randomString(16);
    }

    public static String randomString(int length) {
        char[] chars = "QWERTYUIOPLKJHGFDSAZXCVBNMqwertyuioplkjhgfdsazxcvbnm1234567890".toCharArray();
        char[] saltchars = new char[length];
        Random random = new SecureRandom();
        for (int i = 0; i < length; i++) {
            int n = random.nextInt(62);
            saltchars[i] = chars[n];
        }
        return new String(saltchars);
    }
    /**
     * 测试
     */
    public static void main(String[] args) throws Exception {

        String test1 = "sa";
        String test = new String(test1.getBytes(), StandardCharsets.UTF_8);
        String data = null;
        String key = KEY;
        String iv = IV;
        // /g2wzfqvMOeazgtsUVbq1kmJawROa6mcRAzwG1/GeJ4=
        data = encrypt(test, key, iv);
        System.out.println("数据：" + test);
        System.out.println("加密：" + data);
        String jiemi = Objects.requireNonNull(desEncrypt(data, key, iv)).trim();
        System.out.println("解密：" + jiemi);


    }
}
